Keyboard



June 16, 1953 H. P. LUHN KEYBOARD 7 Sheets-Sheet 1 Filed Jan. '19, 1949 I FIG. IA

INVENTOR. HANS I? LUHN BY fl/JM Arromvsx June 16, 1953 LUHN 2,642,226

' moms 7 Filed Jan. 19, 1949 7 Shegts-Sheet 2 FIG.3

INVEN TOR. I

HANS F. LUHN ATTORNEY.

June 16, 1953 Filed Jan. 19, 1949 FIG .4

. no.6 x,b i\

H- P. LUHN KEYBOARD 1 7 Sheets-Sheet 3 FIG. 411 I (76 27 :5 {W W WW ATTORNE K June 16, 1953 m. L N 2,642,226

I KEYBOARD Filed Jan. 19, 1949 7 sheets-sheet 4 W INVENTOR.

HANS P. LUHN Z 98 FIG. IO m N w/M ATTORNEY H. P.- LUHN 2,642,226

' KEYBOARD 7 Sheets-Sheet 6 June 16, 1953 Filed Jan. 19, 1949 INVENTOR. 1 HANS R LUHN /%//M Arrows! June 16, 1953 p, H 2,642,226

KEYBOARD 2 Filed Jan. 19, 1949 4 7 Sheets-Sheet 7 INVENTQR. HANS R LUHN ATTORNE X Patented June 16, 1953 UNITED STATES PATENT OFFICE KEYBOARD Hans P. Luhn, Armonk, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application J anuary'19, 1949, Serial No. 71,734

9 Claims.

This invention relates to a keyboard. More particularly this invention relates to illuminated electric keyboards.

It is an object of this invention to provide a keyboard so arranged and constructed that visual distinction is imparted to keys that are depressed into operative position. This objective is attained by providing in the keyboard a mounting for guiding light conducting keys along a fixed path from inoperative to operative position, a light source remote from the keys, and a light path intersecting the line of movement of the keys and extending between the keys and the light source- It is a further object hereof to provide mechanism for selectively imparting colored illumination to the face of depressed keys, and this objective is achieved by providing a plurality of color screens which are shiftable into and out of the light path extending from a light source into the plane across which the keys are operable.

It is a further object of the invention to provide a keyboard having reset mechanism of a highly flexible nature. This objective is attained in a keyboard having a plurality of denominational banks of keys and a latching bail associated with each key bank for latching a depressed key in operative position by providing in such structure means for manually resetting any given bank of keys and electro-mechanical means to which the resetting device of the respective banks may be selectively connected for electro-mechanically resetting such selectively connected banks, without in any Way impairing their manual vreset function.

It is a still further object of the invention to provide a novel keyboard assembly wherein key supporting separators of substantially uniform character may be assembled into a. keyboard structure. This objective is attained by providing a plurality of interfitting key bank separators or supports, each consisting of an elongated body of substantial width and thickness, the separators or supports being adapted for face-to-face assembly so that a plurality of such elements may be united to constitute a keyboard structure.

It is another object of the invention to provide a novel combination of mechanical and electrical elements that will combine functionally to greatly reduce the number of keyboard parts and thereby render possible the assembly of a keyboard with the greatest economy of time and materials.

Other objects and advantages of the invention will appear as the particular description 2 thereof proceeds in'light of the drawings forming a part of this application, and in whichdrawmgs:

Fig. 1 is an elevational view looking towards the face of the keyboard;

Fig. IA is a plan view of a light conducting key constituting a. part of the keyboard;

Fig. 1B is a transverse cross-sectional view through the key of Figure 1A; I

Fig. 2 is a fragmentary elevational view on line Z -2 of Figure 1 Fig. 3 is a cross-sectional view through the keyboard on line 33, of Figure 1;

Fig. 4 is atransverse cross-sectional View on line 4 -4 of Figure 3;-

Fig. 5 is a transverse cross-sectional view on line 55 of Figure 3;

Fig. 6 is a cross-sectional view on line 66 of Figure 3; r

Fig. 7 is a fragmentary elevational view of the lower end of the keyboard structure;

Fig. 8 is a cross-sectional view on line 8-8 of Figure '7;

Fig. 9 illustrates a common reset bar;

Fig. 10 illustrates another common reset bar;

.Fig. 11 is a fragmentary view of a common electrical connector;

Fig. 12 is a fragmentary sectional view through the lower end of the keyboard, showing modified reset mechanism;

Fig. 13 is a fragmentary plan view of reset mechanism taken on line I3-l3 of Figure 12;

Fig. 14-is a fragmentary view of the reset mechanism-taken on line l4-l4 of Figure 1-2;

' Fig. 15 is a View looking towards the upper'edg'e of a key bank separator molding, as from the .line |5|5 of Figure 16;

Fig. 16 is a view of one face of the key bank separator, viewed from line l6l6 of Figure 15;

Fig. 17 is a view of the other face of the key bank separator, viewed from line l7-|l of Figwe 15; I

Fig. 18 is an enlarged longitudinal cross-sectional View of a key, the key being in inoperative or non-depressed position;

Fig. 19 is an enlarged longitudinal cross-sectional view of a key, the keys being in operative or depressed position; and

Fig. 20 is a' transverse cross-sectional view on the line 20-40 of Figure 18.

The keyboard storage device I!) includes a plurality of key banks, each bank containing a plurality of keys. Herein the keyboard is illustrated as consisting'of ll banks of denominational-keys l2, and one bank-of functional keys i l. Each bank of keys is supported on a separator molding it, which itself consists of an elongated body of molded material, such as phenolic resin. The separator has substantial width and the thicknes is such as to accommodate in the faces thereof appropriate guide passages and cavities to accommodate functional operative'parts. For example, in one face of each separator molding are a plurality of guideways i 8 for accommodating the keys of that particular key bank. The guideways G8 are adapt-' ed to confine keys mounted therein to an operative reciprocatory path. The same face of the separator molding has therein a longitudinal passageway 20 constituting alight path, as will appear hereinafter. The opposite face of the separator molding has formed therein a longitudinally extending recess 22, which is designed to accommodate the move-- ment of a key-latching bail, as will appear more fully hereinafter. The same face of the molding has downwardly extending slots Ed, in each of which is adapted to rest a key terminal,"as will appear hereinafter. The-upper end ofeach separator molding has formed thereon a head 26, through'which extends a cylindrical passage 28. Furthermore, each separator molding hasa plurality of transverse passages, which are designed to accommodate tie rods 36, by means of which a plurality of separator moldings may be joined in face-to-face relation to provide an operative keyboard structure.

In each of the key: guideways i8 is mounted a key 34 for reciprocating movement into open and closed position. Each of' the' keys 34 is formed of light conducting material, such as, for example, methyl methacrylate resin, which is known by the trade name Lucite. Lucite has the property of conducting light rays along the length of a body thereof without material loss in a lateral direction.

The keyway intersecting passageway 26 constitutes a light path of-channel form along which light rays may be directed for'illuminating a depressed light conducting key whose-lower end extends into the channel. The-channel may assume any appropriate cross-sectional form for most effectively confining light rays along the path. Herein thepassageway has been-illustrated as having a uniform cross-sectional shape and size along itslength. The size and shape from end to end thereof may, however, vary.

It may prove desirable to provide an aid to the passage of light rays along the passageway 20 to assure that all the keys, even those remote from the light source, receive .an' effective amount of light. To this end a specific aid has been incorporated into the structure. way intersecting passageway 20 may have positioned therein a Lucite light conducting member 35, the position of the same being such that it intersects the path of movement of a key as when the key is depressed. As more clearly seen in Figure 3 of the drawing, the light conducting member 36 is notched along its upper face and the notches 38 are so positioned as to receive and accommodate the lower end of the keys 35 when any one of them is depressed. The upper end 50 of thelight conducting member 36 is exposed to a light source, and as a consequence of this arrangement light rays that fall on the end 40 of the light conducting member are carried along the light conducting member in parallel relation without substantial lateral loss, and if any of the keys are depressed.

The key --The structure herein furthermore so that the lower end of a depressed key extends into a notch 38 in the upper face of the light conducting member 38, the light rays transmitted along the light conducting member are carried into the depressed key where they are deflected by an appropriately shaped surface, and thence along the body thereof and through the exposed operating face. It will be seen that, while all of the keys may have an incidental luminous glow, any of the depressed keys will have a distinctly illuminated face and thus stand out in contrast to keys that are in nondepressed position.

includes common means for illuminating all of the light conducting channels of a plurality of key banks, and furthermore means for selectively shifting color screens into the path of light between the light source and the light conducting channel. Thus, within the longitudinal cyilndrical passage formed at. the head 26 of a plurality of assembled separator units, is...positioned a lamp 422, which is preferably of an elongated type, .so that a substantially equal amount of illumination is provided for each :of the light conducting mem bers across the entire width of the keyboard. The lamp herein is encased in a reflector shield M, which has a longitudinally extending light window 48 arranged in alignment, with the upper end iil of the light conducting members 36.

Arranged. about the reflector 44 is a color band ring 48, which may be particular to an individual bank or common to a plurality. of banks. 3A segment of the color band ring is adapted to hold a color band 50. vTheband may consist of. a singlexcolor filter or a'plurality thereof. Thus, the filter 58a, for example, may pass only red lightywhile' the filter 501) may pass only green light. By operating the color band ring projection 52 either one or the other color filter may be moved into the path of light between the lamp 42 and the adjacent ends of the light conductingchannels 20. It follows, therefore, that either adjacent banks or adjacent groups of banks may be. illuminated differently for distinguishing the depressed keys of such banks even more sharply.

The keyboard device herein is of the type designed for the control of electrical instrumen talities found in certain types of intelligence transmittingdevices and computing machines, and consequently, it has been provided with appropriate structure-for completing electrical circuits for operating such instrumentalities upon the depression of a key or keys in any given bank or banks. "Furthermore, mechanism has'been provided for temporarily latching a key in depressed circuit making position.

Each bank 'of keys has associated therewith a common key bail 54, which,- as more clearly shown in Figure 6, is mounted by means of mounting ears 56 at a plurality of points 2i along the length of its associated separator molding. The free end 58 of each bail is urged towards its associated separator molding by means of a spring 60 which has one end thereof attached to the bail and the other endto an anchor 62. As a'consequence of this mounting, the bail is yieldingly urged into key latching position and is, therefore, effectiveto hold a key of its bank in depressed position until either another key in the samc'bank is depressed or reset mechanism is operated for its release.

Each key has a key latching cam or contact plate E l fixed to one face thereofi .The'cam is formediof conducting material and iS'iOfSlICh configuration as to present anotch 66in one'edge thereof to the inturned lower'free edge58 of the latching bail when the key is'in' its inoperativeposition. Immediately-above the notch 56 is an outwardly inclined cam surface 68, which normally overlies the inturned free edge 58 of the latching bail. The cam surface 68 terminates in a shoulder which is designed to hold a key in depressed position by engagement with the lower face of the free edge 58 of the key latching bail.

The depression of a key will." force thecam surface 58 into contact with the free inturned edge 58 of the bail' and continued; downward movement'of: the key will swing the bail outwardly about its'pivot at the mounting ears 56 and against the tension of the spring 60. When the free edge of the bail has passed the camming surface 68, the spring 68 will serve to positively draw the free edge 58'of the bail into contact with the latching shoulder 70 andthereby effectively retain the key in depressed position. The key will remain latched under the bail until another key in the same bank is depressed or until reset mechanism is either manually or automatically operated to rock the bail and thereby release the key.

A depressed key will return to its normal inoperative position under the influence of a spring 12, which is carried by a recess 14 in one face of the key. Each key has associated therewith a conductor and terminal 15, and thesame is provided with a lateral offset 16 which extends into the recess 14 of the key and engages the latching cam 64. Extending upwardly from the offset of the terminal is a staff 18, about which the spring 12 is positioned. The staff 18 extends upwardly into a clearance slot 80, which is formed in the .key and which opens downwardly into the recess 14. The key terminal is in conductive contact with the key latching cam and contact plate 64.

Each bail has a bail terminal associated with opposite ends thereof. As best seen in Figure 3 of the drawing, one terminal 82 is carried by an associated separatorand extends downwardly therefrom in proximity to the upper end of an adjacent bail. Another terminal 84- is fixed to and extends downwardly from the lower end of the bail. One of the terminals 82-or 84 is normally. connectedto a source of electric current. When no key of a given bank is depressed, there is a current path from terminal 82, through the key latching bail, and through the bail terminal 84. In this regard it is to be noted that the inturned edge 58 of the bail lies opposite the notch 63 in the key latching cam 64 when thekey is in its inoperative position, and consequently, the bail is insulated from the key latching cams by the intervening space. Should, however, a key be depressed, the key latching cam and particularly the shoulder 10 thereof will lie in conducting contact with the inturned lower edge 58 of the bail, and as a result of this connection a current path will be established through bail terminal 84, the bail, the key latching cam of a depressed key and through the key terminal 15 to a conductor (not shown).

By reference to Figure 5 it will be specifically noted that the bail at the left of the figure is in circuit making contact with the bail terminal 82. This is the normal position of these respective parts before any keyof a bank has been depressed. The-bail and, bail terminal-relationship .shown at the right of Figure 5is that which prevails when a key of that particular bank has been depressed. It will be noted therein that the bail has been swung to the right, and as a consequence contact between the lower inturned edge of the bail and the bail terminal has been broken.

It will be understood that each bail is provided with terminals and that each key has an associated key terminal. Operating current is impressed on a key terminal by depressing the key and such current may be taken from the individual key terminal. For certain modes of operation. however, it may be convenient to use a common connector for connecting the denominational rows of a. plurality of banks. The common connector 86 consists of a conducting strip having a plurality of cars 8! struck upwardlyfrom one face thereof, each ear being so located and arranged as to engage with the bifurcated lower ends 93 of the key terminals. The conducting strip 83 is of such length and has a sufficient number of upstruck ears 8? to extend across the entire keyboard and to contact with the bifurcated ends of all the keys in any given row. The connector 8&3 may have a ferrule 82 at one-end thereof for receiving the end. of a conductor, although the connection may be made to one of the ears of the outer key terminal. In this regard it may be noted that the lower end of the key terminals provide a pair of cars 98a and 90?), which afford means for attaching separate leads to a single terminal if the operation being performed should require such connections. In effecting this, one of the ears, 99a or 98b, of each terminal is bent laterally so that the ears are offset with respect to one another and are thereby accessible for making separate plug wire connections.

Allusion has been made herein to a novel combination of mechanical and electrical elements that combine functionally in support of each other with a resultant reduction in parts and simplification of the keyboard structure. These desirable qualities flow from the novel relation of the key bank separator, the keys, and the few related parts which provide key banks that are complete operative units adapted for assembly into a keyboard structure of any desired number of banks. These elements and combinations are now to be described with particular reference to Figures 15 through 20.

. Figures 15 through 17 show the details of a molded key bank separator or support, the same having been referred to hereinbefore by the reference numeral Hi. In brief recapitulation, it will be remembered that the separator has a plurality of key guideways I8 which are intersected by a generally longitudinal light passage or channel 20 on one face thereof and on the other face thereof the body is relieved in a longitudinal direction to provide a recess 22 to accommodate an adjacent key bail. Thereunder are a series of transverse slots 24 extending downwardly to provide clearance for key terminals.

In further detail, it will be observed with par ticular reference to Figure 16 that the separator face therein shown includes a slot 2| at each end thereof for receiving key-latching bail mounting ears. Directly under the slots 2| are through passages 23, through which the bail spring 60 may be extended for anchorage against the opposite face of the separator.

At the lower end of each key guideway [8 is 7 a seat 25, which is adapted to support the lower end 90 of the key terminals 15. Each seat has therein a passage 21 adapted to receive a terminal spur M (Fig. 12) for anchoring the terminal in position on its seat. The lower bail terminal 8 is mounted on the seat 29, while the upper bail terminal 82 is mounted on the seat 3| at the upper end of the separator body. The intermediate seats are all-designed for the reception of operative key terminals. A clearance 33 is provided at one face of the head section 26 for the reception of the color band rotating projection 52.

The opposite face of the separator body is shown in Figure 17 and the same is distinguished from the first face thereof by the aforementioned clearances 22 and 24, which are provided for key bail clearance and for the accommodation of terminal elements respectively. Each separator has a through transverse passage 35 at the lower end thereof, through which the reset bails 9t, 98, i25 and I28 may extend and in which they may be reciprocated during reset operations. Each separator has a seat formed at opposite ends thereof for mounting the same in a supporting frame or casing. Thus, an upper seat 31 is adapted to support the upper end of the separator, while a lower seat 39 is adapted to support the lower end of the separator in operative position on the keyboard casing I90 or on a separator frame.

The structure of the keys 34 normally mounted for operation in the separator key ways i8 is such as to provide a mounting for electrical elements that are rendered operative by key manipulation. The key recess M opens outwardly through three faces of the key and provides a cavity in which current conducting members are carried. Specifically, it will be observed that the recess i l not only has an upwardly extending clearance slot ill but also a ridge M in the bottom thereof for more securely anchoring the contact plate M. The contact plate 64 has inturned ends 65 and 61. The inturned end 65 includes two fingers which lie in contact with the upper wall of the key recess 14 and a third finger 89, which extends upwardly and inwardly into the clearance slot 86. This structure firmly positions the upper end of the contact plate 6 6.

The lower inturned end of the contact plate 64 lies in contact with the bottom wall of the key recess, and this end of the plate is centrally slotted to straddle the rib Bl that extends upwardly from thebottom wall of the recess. By this means the lower end of the contact plate is firmly and. accurately positioned.

As more particularly shown in Figures 18 and 19, the key terminal member 15 extends upwardly along one face of the key and the terminal offset it enters the key recess 14 at one of its open sides relatively removed from the face in which the contact plate 64 is seated. The reduced staff 78, which extends upwardly from the offset portion of the upper end of the key terminal, extends freely through the slot formed between the two inturned fingers at the upper end of the contact plate 6 1, so that the key may be reciprocated with respect to the terminal staff it and thereby be brought into contact-making or reset position. The spring 12, which surrounds the terminal staff 78, normally retains the key 34 in its non-depressed or inoperative position. Inasmuch as the terminal staff spring 12 is in contact at one of its ends with the inturned end 65 of the contact plate 64, and at its other end with the offset or inturned shoulder 76 of the key terminal, it will be apparent that a current path is established from the contact plate 64, through the spring '12 and to the terminal 16. It further follows that depression of a key will place the spring 12 under com pression and thereby assure even better conduc tive contact between the contact plate 64 and the key terminal F6. The foregoing key assembly is such that the electrical elements are carried by a mechanical functionalelement, which thereby eliminates separate supporting structures and the like.

One of the objectives of the invention is the provision of a keyboard structure having the utmost resetting flexibility. Accordingly, each key bank is provided with manual reset means and in an optional form of the reset structure there has been provided a plurality of common reset bars, to which any one of the key banks may be operatively connected at the option of the operator.

Each key latching bail 54 has attached thereto a manual reset key 94, this key being mounted on the lower end of the bail and being such that a manual operation thereof will rock the bail about its pivot ears 5% and thereby manually release any key that may have been latched in depressed position. The reset mechanism may optionally include a pair of dielectric bail reset bars 96 and 98, which extend transversely across the bottom of the keyboard and which are common to the several key latching bails of the keyboard banks. The reset bars are mounted for reciprocating movement on a reset bar separator I00.

The reset bars 96 and 98 extend laterally beyond the keyboard at one side thereof and provide in their extending ends a connection for an electromagnetic operating mechanism. Particularly the extending ends of the bars have slots formed therein for receiving the end of a reset operating arm I04 and "Ma (Figs. 1, 2 and 8). Herein the bar 96 has a slot 102 therein, in which is positioned the end of an upper reset arm I04 and the bar 98 is similarly connected to a lower operating arm [0411. The operating arms I04 and Ma are mounted on a bracket 106 for rocking movement under the influence of the core of an associated solenoid to which the arms are connected. Thus, the reset operating arm IDA is rocked in the bracket upon reciprocation of the solenoid core Hi8, while the arm lMa is rocked in its supporting bracket upon reciprocation of the solenoid core H0. It will appear, therefore, that energization of the solenoid H2 or the solenoid il will cause the cores H38 and H0, respectively, to operate therein, and consequently, the associated bail reset bars will be reciprocated. Appropriate circuit connections for controlling the operation of the solenoids H2 and [M are provided :tO include a pair of functional keys in the bank [4, whereby the solenoids may be selectively energized.

The reset bars 96 and 98 each has a series 'of teeth H6 and H8, respectively. The teeth on the reset bars are positioned to intersect the plane of the lower free edge of the latch bails when either of the reset bars is reciprocated. The number and position of the .teeth onthe reset bars determine the banks controlled by the bars; Thus, the reset bar 96 is shown as having four teeth at its extreme righthand end, while the bar 98 has four teeth on the extreme lefthand end thereof. As a consequence of this arrangement of teeth,

reset bar :96 will control the first four denominational banks, while reset bar 98 will control the last four banks. It is to be understood, of course, that the number and arrangement of the teeth H6 and H8 herein have been arbitrarily selected merely for the purpose of illustrating the principle of operation.

Inorder to lend a greater degree of flexibility to the key resetting mechanism, resort maybe had to the arrangement shown in Figures 12 through 14. In these figures is illustrated a reset.- ting arrangement whereby any one of the :key latching bails may be operatively connected with either of two electro-magnetically operated reset bars. On the other hand, the arrangement herein is such that all of the bails may be manually operated at all times quite independently of the electro-magnetically operated reset bars. In Figure 12 is shown a key latching bail I28, which has a reduced lower end I22, on which end is adjustably mounted a manual resettingkey' I24. Extending transversely of the common projecting bail ends I22 are a pair of reciprocating reset bars I 26 and I28, mounted for reciprocating movement in a reset bar separator I30.. The reset bars I26 v and I28 project laterally beyond one side of the keyboard to provide connections for electromagnetic bar operating levers. Specifically, the bar I28 has in its extending end a slot I32, which is adapted to receive the bar rocking lever I34. The bar I36 has in the extending end thereof a slot I38, which is adapted to receive the bar rocking lever I40. The levers I34 and I40 are mounted for rocking movement upon reciprocation of the cores of the solenoids I42 and I44, respectively, to which they are operatively connected.

. 'From the foregoing it follows that energization of the solenoidsI42 and I44 and reciprocation of their respective solenoid cores will reciprocate the resetting bars I28 and I26. Each of the resetting bars has a series of projections I46 extending upwardly along the entire upper edge thereof and these projections are so positioned as to contact and rock a connecting ear forming a part. of a shiftable manual reset key I24.

The manual reset key I24 has a relatively .elongated throat I48, which guides the key for sliding movement along the reduced end of the key bail I22. The reduced end of the key bail has formed in the upper face thereof a series of three notches I50, which serve to locate a detent member I52, which is under constant pressure of the spring I54. A sufliciently large segment of the detent member I52 extends through an aperture in the wall of the throat I48 to establish temporary holding contact between the detent member I52, and one of the notches I58 in the reduced end of the bail I22. Consequently, it is possible to shift the manual reset key I24 into a selected one of three positions correspondingto any one of the notches I50. The detent member I52 will serve to maintain the adjusted position of the reset key when shifted into registration with one of the three notches. The reset key has a. depending portion, which includes a pair of shoulders I56 and I58. The depending shoulder portions of the key are spaced sufficiently to straddleand receive therebetween the solenoid operated reset bars I26 and I28. Thus, when themanual reset key I24 is in'a reset rod straddling position, as shown in Figure 12, neither of the reset bars will influence the operation of the bail, but the bail may be manually rockedfor resetting a key that maybe in latchedpositione Should it be desired to connect a bail with the lower of the two reset rods, it is only necessary to shift the reset key into an upper position wherein the depending shoulder I558 will lie in the plane of reciprocation Of the projection I46, so that upon reciprocation of the reset bar I28 the bail will be rocked to key releasing position. On the other hand, should it be desired to connect the bail for operation by the reset bar I26, such connection can be easily achieved by shifting the reset key to its lower position of adjustment whereby the shoulder I55 will be influenced by the projection of the upper reset rod I26.

The reset bar connecting function of the shiftable reset keys will be more apparent from an inspection of Figure 13, wherein the keys I58, I62, H34 and IE5 are in a neutral position and are, therefore, conditioned for manual operation only. The keys I68, I10, I72 and I14 are in the innermost position and, therefore, effectively connect their respective key latching bails to the lower reset bar I23. The keys I16, I133, I33 and IE2 are in their extreme outer position of adjustment, and consequently, operatively connect their associated key latching bails with the upper reset bar I25. It follows, therefore, that the resetting function of any bail or any combination of bails may be either manually or both manually and mechanically performed depending on the adjusted position of the manual resetting keys.

The light transmitting property of the keys has been referred to hereinbefore, and it is one of the companion objectives of this invention to impart a light dispersing character to the Working face of the keys. Ordinarily, with a plane light transmitting face, the light rays Will leave the working face of the key stem in substantially parallel relationship. In order to render the light rays clearly visible from positions disposed at an angle to the axis of the key stern, it is the purpose herein to modify the working face of the keys so that the light will be diffused and, therefore, become visible from any position of observation. The mereroughening of the key face, as bysand blasting, will in some measure achieve this objective. Light refracting materials may be fixed to the working end of the keys. Translucent and transparent materials of this type may be made of a variety of substances, as, for example, Celluloid, acrylic plastic, polystyrene, Vinylite and the like. These materials are composed of a mixture of chemicals having different refractional indices which cause a breaking up of the light rays as they pass through the material.

In a specific application of the idea, as shown in Figures 1A and 1B, the face of the Lucite key 34 has been given prism form characteristics by cutting thereon a series of concentric circles E64 with resultant inverted V-shaped ridges I88. This prism-like surface will effectively refract the light'being projected through the face of the key.

In order that the denominational value of the key may be clearly indicated both when the key is in an'unilluminated inoperative position and in an illuminated operative position, it is contemplated that a character I86 be represented in contrasting. paint or other material on the face of the key. Most specifically, the character may be engravedinto the face of the key and the ou line ofthe engraved character may be filled with a plastic material or a paint of suitable contrasting colon. Thus, thevalueof a non-depressed key may be easily ascertained by noting the character thereonintits natural color. The denomination of an illuminated depressed key will be apparent by the contrast of the opaque facial character with the surrounding illuminated area of the key face.

The ends, back, and bottom of the keyboard mechanism are suitably encased, but for clarity of illustration only a portion of the casing has been illustrated. Suitable end casings are provided and a back and bottom casing 590, on which the separator seats 31 and 39 rest, contitutes the main support for the keyboard structure. As hereinabove suggested, suitable cable passages are provided in the casing for access of necessary cables or connecting wires.

Assuming the keys of the keyboard to be reposed in inoperative position and the bail terminal $4 to be in connection with a suitable source of current, operation of the machine may proceed substantially as follows:

Current impressed on the bail terminals M will flow through the key-latching balls thence through the upper bail terminals 82, through any suitable instrumentality (not shown) and to the other side of the line. This current path is established because of the position of the key-latching bails 54, as shown at the left in Figure 5. It will be noted that the bail springs 60 retain the bails in an inward position in relation to their respective separators, and consequently, the inturned edge 58 of each ball is in contact with the upper end of its respective upper bail terminal 82. At the same time, reference to the bail section at the left of Figure 4 will show that no current can pass from the inturned edge of the bail to the key contact plate 65, for the reason that the notch 66 in the contact plate is positioned opposite the inturned edge of the 'bail, thereby providing an insulating space.

Upon depression of a key in any given bank, the associated parts will be disposed as shown at the right of Figures 4 and 5. The cam face of the key contact plate in this position has been effective to swing the bail 5 5 in a counter-clockwise direction wherein the bail overlies the shoulder of the contact plate and forms therewith an electrical circuit. In this position the key will be held in depressed position. A comparison of the bail position at the right of Figure 5 will show that the bail 5% has been swung in a counter-clockwise direction and the contact between the inturned edge of the bail and the upper end of the bail terminal 82 has been destroyed. Consequently, a circuit path is established from the lower bail terminal 8d, through the bail 55, through the key contact plate -64, and consequently, through the terminal of the key that has been depressed.

Depression of a key will project the lower end thereof into the path of light traveling through the light channel 20 and specifically herein through the light transmitting member 36 that has been positioned in the channel. Previously, of course, the color selecting finger 52 may have been manipulated to bring one of the color screens 50a or 5% into the beam of light emanating from the light source 42 and passing through the light window 64 into the light transmitting channel under the bank of keys. As a result of this relationship, the face of a depressed key will be well illuminated and have imparted thereto a distinction setting the key oif from all other keys of the bank, so that a mere glance at the keyboard will appraise the operator of any key that has been depressed.

All keys that have been depressed will remain in a depressed" position with the resultant "main-a tenance of the current paths that have been es-q ta'blished, and a keyboard may remain set in such position as long as desired for repeated cyclic operation. However, should it be desired to reset any of the banks, such operation may follow at the option of the operator either. by manually operating the reset keys 94 (Figures 1 through 10) or I24 (Figures 12 through 14)."

Electro-mechanical resetting of any selected number of banks may also be resorted to byuse of the electro-mechanically operated reset bars, as hereinbefore described. It follows, therefore, that the keyboard has complete flexibility. Any one of the banks may be reset at anytimev and thereby removed from operation, other banks may remain set, and additional keys may be depressed for integrating into the system additional or different data at any time as conditions may require.

I claim:

1. Ina keyboard, a plurality of light conducting keys arranged in a plurality of separate banks and being mounted for shifting movement along a fixed path, a light source common to said banks remote from said keys, an individual light conductin member associated with each bank of keys, said light conducting members lying in the path of movement of their respective keys and extending between said keys and said light source, a separate color screen associated with each light conducting member, and means mounting said color screens for movement through the path of light falling from said common source of said light conducting member.

2. In a keyboard, a plurality of light conducting keys arranged in banks and mounted for shifting movement along a fixed path, a light source common to said banks remote from said keys, an individual light conducting member in the path of movement of the keys of each bank and extending between said keys and said light source, and a separate color screen associated with each light conducting member, each color screen having. a plurality of color filters selectively movable into the path of light falling from said light source to said light conducting memers. 3. In a keyboard, a plurality of light conducting keys arranged in a plurality of separate banks each containing a plurality of keys, means for mounting the keys of each bank for shifting movement along a fixed path, a separate light conducting member associated with each bank of keys and lying in the path of movement of the keys thereof, a common light source arranged along one end of said light conducting members, color screens. individual to each light conducting member arranged transversely of the bank of keys, and means mounting said color screens for movement through the path of light falling from said light source against the ends of said light conducting members.

4. In a keyboard, a plurality of light conducting keys arranged in separate banks consisting of a plurality of keys each, the keys Of each bank being mounted for shifting movement along a fixed path therein, a separate light conducting member associated with each bank, a recess in said light conducting members for each key of the respective banks adapted to receive an end of said keys in one limit position of movement, a common light source extending transversely of said banks and being positioned adjacent one end of said light conducting members, color 13 screens individual to each light conducting member, and means mounting said color screens for movement through the path between said light source and the adjacent ends of said light conducting members.

5. In a keyboard, a plurality of light conducting keys arranged in a plurality of separate banks each containing a plurality of keys, means for mounting the keys of each bank for shifting movement along a fixed path, separate light conducting channels associated with each bank of keys and lying in the path of movement of the keys thereof, a common light source arranged along one end of said light conducting channels, color screens individual to each light conducting channel arranged transversely of the bank of keys and means mounting said color screens for movement through the path of light falling from said light source into the ends of said light conducting channels, each color screen including a plurality of color filters.

6. A light conducting key having a prism like surface formed of inverted U-shaped ridges constituting an operating face and having an opaque character in the face thereof in a plane below the prism form surface.

7. In a keyboard assembly, a key bank support having an elongated body of substantial width and thickness, a plurality of parallel'open guide grooves in one face of said body for guiding keys therein in a confined reciprocatory path, an open slot intersecting all of said grooves at one end thereof, light conducting keys in said grooves, and a light conducting bar in said slot.

8. In a keyboard assembly, a key bank support having an elongated body of substantial width and thickness, a plurality of parallel open guide grooves in one face of said body for guiding keys therein in a confined reciprocatory path, a slot intersecting one end of said grooves, a notched light conducting member in said slot with the notches thereof in registration with said grooves, and a light conducting key mounted in 14 each of said grooves for the projection of one end thereof into an underlying notch in said light transmitting member when said key is depressed.

9. In a keyboard assembly, a plurality of key bank supports, each support having an elongated body of substantial width and thickness, a plurality of keyW-ays in one face of each of said supports for guiding keys therein in a confined reciprocatory path, a cylindrical passage at one end of said supports, a slot in each support intersecting one end of the keyways therein, a notched light conducting member in each of said slots having the notches thereof in registration with said keyways, a light conducting key mounted in each of said keyways for the projection of one end thereof into an underlying notch in said light transmitting member when depressed, and a common light source in the cylindrical passage formed at the end of said supports, and means for securing said bank supports in face-to-face relation to constitute a keyboard.

HANS P. LUHN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,084,667 Tallmadge Jan. 20, 1914 1,414,978 Bumstead May 2, 1922 1,514,954 Crumpton Nov. 11, 1924 1,554,048 Thomas Sept. 15, 1925 1,808,213 Eichenauer June 2, 1931 2,059,652 Pott Nov. 3, 1936 2,174,150 Beria Sept. 26, 1939- 2,176,640 Payne Oct. 17, 1939 2,234,954 Bergman Mar. 18, 1941 2,255,909 Avery Sept. 16, 1941 2,301,419 Lew Nov, 10, 1942 2,346,988 Noel Apr. 18, 1944 2,476,257 Hoif July 12, 1949 2,493,829 Paul Jan. 10, 1950 

